Switch



K. REHM Nov. 22, 1966 SWITCH 4 Sheets-Sheet 1 Filed April 20, 1965 IN vszvron Karl Rehm K. REHM Nov. 22, 1966 SWITCH 4 Sheets-Sheet 2 Filed April 20. 1965 INVENTOR Karl Rehm ATTORNEYS Nov. 22, 1966 K. REHM 3,286,812-

SWITCH Filed April 20, 1965 4 Sheets-Sheet 5 v 2 Fig. 4 :'1 l:

INVENTOR Karl Rehm ATTORN EYS Nov. 22, 1966 K. REHM 3,286,812

SWITCH Filed April 20, 1965 4 Sheets-Sheet 4 MAINS RECTIFIER AND TRANSFORMER A 22\" WINDING T SELECTOR PULSE FORMER PULSE w POLARITY REVERSER ELECTROMAGNET MEANS 4, I I F I I I I I I CONSTANTLY PULSE I PULSE CONSTANTLY I I ENERGIZED ENERGIZED I ENERGIZ ED ENERGIZED I WINDING WINDING I WINDING WINDING I I I I I L I L D) I \ELECTROMAGNET MEANS 5 F Ig. 6

IYVENTOR.

ATTORNEYS United States Patent 3,286,812 SWITCH Karl Rehm, Konstanz, Germany, assignor to Telefunken Patentverwertungsgesellschaft m.b.H., Ulm (Danube), Germany Filed Apr. 20, 1965, Ser. No. 449,421 Claims priority, application Germany, Apr. 22, 1964, T 26,054 12 Claims. (Cl. 198--31) The present invention relates generally to the sorting and conveying art and, more particularly, to an electromagnetic switch or gate arrangement in conveyors for flat articles, such as letters or documents, in which the switch comprises a switch blade of ferromagnetic material, at least at its front edge, and is associated with electromagnets arranged at both sides of the blade in the region of its front edge.

This type of device is already known, for example as disclosed in German Patent No. 1,103,250. In this device, a switch is disclosed which comprises a switch blade mounted at a branching point in the conveyor path as well as two electromagnets coacting with a blade tip of ferromagnetic material. Each of the electromagnets includes a round bar provided with a winding and acts on the switch blade with only one of its two poles. Mounted in the region of the two electromagnets, but upstream of the conveying direction, are two conveyor rollers, one of which is adapted for pivoting against a spring force. At the exit from the branching point, there is mounted a second pair of conveyor rollers in the one conveyor path of which one roller is likewise mounted for pivoting against a spring force. Both the first and the second pair of conveyor rollers can be driven at a higher speed than that which corresponds to the converging speed of the articles. By this means, the effect is obtained that the gap between two successive flat articles is increased in the switching zone so that, with an appropriately high conveying speed, a large number of flat articles can be processed per unit of time, even with switches which switch-over comparatively slowly.

In this known device, a first embodiment is constructed in such a manner that the two electromagnets are energized alternately. The switch moving magnetic force is equal to the switch retaining magnetic force and must be maintained for as long as the switch blade is to bear against the electromagnet in question. Such a construction is not very advantageous, however, because in the interests of rapid switching-over of the switch blade, at

large switch moving magnetic force is necessary and this" large force may, in some circumstances, have to be maintained in full over a long period of time although only a lesser continuous force would be necessary to hold the switch blade when the switch blade is hearing against one of the electromagnets.

In order to overcome this difliculty, a second embodiment of the known device is constructed in such a manner that the switch blade is made of a non-magnetic material at its later-a1 faces and contains a small permanent magnet at its tip. The two electromagnets are connected insuch a manner that their two cores have poles of the same polarity opposite one another. The switching-over of the 3,286,812 Patented Nov. 22, 1966 "Ice time. If, on the other hand, the permanent magnet is given appropriately small dimensions with respect to the desired switching times, the holding force of the switch blade becomes inadequate and the entire switch arrangement becomes practically useless.

With these defects of the prior art in mind, it is a main object of the present invention to overcome the aforementioned difficulties and, at the same time, to render it possible to substantially increase the switching-over speed of the switch.

Another object of the invent-ion is to provide an arrangement of the character described in which the capacity is substantially increased without increasing the conveying speeds of articles being handled.

These objects and others ancillary thereto are accomplished in accordance with preferred embodiments of the invention wherein an electromagnet arrangement is provided which has a constantly energized portion for retaining the switch in one or the other position thereof. In addition there is a temporarily energized portion for moving the switch from one to the other position. A plurality of electromagnets is provided.

Each of the electromagnets comprises a constantly energized winding for retaining the switch in one of its positions, in addition to one or more pulse energized windings for moving the switch from one position to the other. Means are provided to effect a compensation for the constant flux in the particular magnet against which the switch blade is hearing when switch-moving pulse energization of the opposite magnet takes place.

The invention is based on the realization of the fact that a rapid switching-over of the switch blade from one of its positions into the other is essentially only possible if a complete compensation for the constant flux is effected in the electromagnet opposite to the magnet which is energized for switch moving, It is assumed that there is a specific, but selectable switch moving energization, to the value of which the means for compensating the magnetic flux can be adapted. As a result of this compensation, it is possible, on the one hand, to effect the energization of a magnet in a pulse-like manner for a switching operation (switch moving energization) and so to manage with low energizing powers and, on the other hand, to achieve very high switching speeds for the switch blade.

Since the switching speed of the switch can be thus increased, the capacity of the arrangement can be substantially increased without increasing the conveying speed of the articles in order to provide the moving components of the arrangement with a long life. This can only be realized by appropriate reduction of the gaps between two successive articles. This requires a switch which switches over correspondingly quickly and this the present invention accomplishes.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a sectional view of a switch arrangement according to the present invention and taken generally along the plane defined by reference line 1-1 of FIG- URE 2.

FIGURE 2 is a side elevational view taken substantially along the plane defined by reference line IIH of FIG- URE 1.

FIGURE 3 is a sectional view of a switch blade.

FIGURE 4 is a schematic view of one electromagnet arrangement according to the present invention as viewed in the conveying direction.

FIGURE 5 is a schematic view similar to FIGURE 4 of another electromagnet arrangement.

FIGURE 6 is a block diagram of a circuit for using the present invention.

With more particular reference to the drawings, FIG- URE 1 shows a conveyor trough lassociated with elec tromagnets 2 and 3, the cores 4 and 5 of which extend as far as the conveying path for the letters or documents. Downstream of these two magnets, the conveying path branches into conveyor troughs .6 and. 7. Movably mounted on the fixed guide web 8 between these two conveyor troughs 6 and 7 is a switch blade 9. The two end positions of this switch blade are determined by the abutment of the leading portion of the blade against the poles of the magnet cores 4 and 5. includes two steel plates 10 and 11 which are connected at their leading edges. A Vulkollan tongue 12 (a synthetic product) with little inherent rigidity serves to mount the steel plates on the guide web 8. One end of the tongue is fastened between the two steel plates 10 and 11 in the vicinity of the leading edge of the switch blade and the other end is rigidly connected to the guide web 8. The length of the steel plates 10 and 11 is such that their free ends bear against the guide web 8. As a result, accurate guiding of the switch blade 9 is assured. In order to obtain a short switching-over time, the switch blade is made very short. FIGURE 3 represents a scale of about 5:1. It would also be possible within the scope of the invention to make the side walls of plastic material instead of the steel plates 10 and 11. In this case, however, it would be necessary for the leading edge of the switch blade 9 to include ferromagnetic material. The magnet cores 4 and 5 and the windings provided This switch blade 9 4 In the second example of the device according to the invention, as shown in FIGURE 5, constantly energized windings U and D' are likewise provided which are connected in series and again connected to the ,direct.

example A' originating from one magnet core 4, in

the example, passes through the switch blade 9 into the opposite magnet core 5 where it causes compensation for the constant magnetic field, while the rest of the magnetic,

flux A' is closed through the switch blade in the longitudinal direction thereof, from'the top downwards;

-The mode of operation of the device according to the invention is as follows. It will be assumed that the constant magnetic field of the switch arrangement is provided and the switch blade is lying against the magnet core 5 in the position illustrated in broken lines in FIG- URE 1. Iffa letter or document now arrives in the conveyor trough 1 for delivery into the conveyor trough 7,

a signal is transmitted by an allocation circuit (not illustrated) to the proper pulse voltage source V and the latthereon are illustrated diagrammatically in FIGURES 4 i and 5. These magnet cores preferably include soft iron. The remanence of this soft iron should be as low as possible because the time of erection of magnetic field depends on this remanence. As a result, it is possible to demagnetize the cores substantially completely when compensating the switch retaining flux, which contributes greatly to a high switch-over speed for the switch blade. As already mentioned at the beginning, these magnet cores 4 and 5 are constructed in such a manner that, in conjunction with the switch blade 9, closed magnetic circuits are always formed.

. Each of the magnet cores. 4 and 5 contain two constantly energized windings D and D (magnetic fluxes D D These constantly energized windings are connected in series and are connected to a direct voltage V Because of the E-shaped construction of these magnet cores, these two windings on one core are wound in different senses. Furthermore, each of the magnet cores comprises series-connected pulse energized windings A and A (magnetic fluxes A A and series-connectedv same type have different senses of winding also applies to the last two types of winding mentioned.

In this example, the reluctance of the switch blade 9 has such a low value that the magnetic flux (A or bA of a magnet core is closed essentially through the leadingedge of the blade and only a negligible fraction can pass-- transversely through this into the opposite magnet. As already mentioned, the constantly energized windings D and D have such a magnetic action that like magnetism prevails at opposite poles of the magnetic cores. The pulse energized windings A and A are connected in such a manner that their flux reinforces the constant magnetic field, while the counter-energized windings are connected in such a manner that their flux counteracts the constant magnetic field in each case.

The pulse energized windings A and the two legs.

ter is simultaneous-1y connected to the pulse energized windings A or A'.;. This voltage source delivers to the windings A or A; a pulse of defined magnitude, with the polarity assumed in FIGURES 4 and 5. A flux A or A develops in the magnetic core 4 and exertsan attraction force on the switch blade 9. Since, as a result of the means described, a compensation for the constant flux (D or D" occurs simultaneously in the magnet core 5 and this magnet is demagnetized as a result, the switch blade strikes at high speed (2 msec.) against the poles of the magnet core 4, and thus assumes the position-shown in solid lines in FIGURE 1. If the switch has to be switched back into itsother position at a later moment,

the pulse voltage source is connected to the other pulse energized winding A or A' Thus, a very advantageous embodiment of the inven tion is provided in that both electromagnets are constructed in such a mannerthat, in cooperation withthe switch blade, they form a closed magnetic circuit. This is based on the recognition of the fact that only in a closed magnetic circuit can 'sufiiciently great forces ,be'

exerted on the switch blade with energizing power which with three legs as illustrated in FIGURES 4 and 5.

Naturally, however, it is fundamentally also possible to:

use another form of the core, for example, a yoke with According to a further feature of the invention, the fluxes produced in the air gaps by the constant magnetic field are oppositely directed at opposite points. As a result of the like polarity of the oppositely disposed elec- Although it is perfectly possi'ble,.within the conceptof the invention, to use a permanent magnet to produce the constant flux, nevertheless, because of the-requirement that it should be possible to adjust the constant field strength, it is an advantage 'to-use an electromagnet for this purpose. The windings for the constant magnetic field are then preferably wound in such a sense that the'magnetic flux produced bythem is in the samejdi- 'tromagnets a very high; holding force is produced by rection as that of the pulse energized windings of a switch-moving magnet.

An advantageous further feature of the invention is that one or more counter-energized windings, which are energized at the same moment as the pulse energized windings of the opposite electromagnet in each case, are provided as means for compensating for the constant energizing flux in each electromagnet.

These counter-energized windings are electrically connected to the pulse energized windings of the opposite magnet, preferably being connected in series therewith.

A very advantageous possibility for the construction of the device according to the invention is that the magnetic characteristics (reluctance) of the switch blade are so arranged that the magnetic flux passing through it from a pulse energized electromagnet to the opposite magnet is so great that it compensates for the constant flux of this magnet. This construction according to the invention is based on recognition of the fact that it is possible, with a very high reluctance of the switch blade, to use the pulse energized flux to compensate for the constant flux in the opposite magnet, The fiux originating from the pulse energized magnet is divided, in inverse proportion to their reluctances, between the switch blade on the one hand and the non-energized switch moving magnet or the intervening air gap on the other hand. In order to allow a high proportion of the flux produced in the pulse-energized magnet to reach the opposite magnet, it is required that the reluctance of the air gap between the non-energized switch moving magnet and the switch blade bearing against this should be considerably lower than the reluctance of the latter. Thi in turn is only possible with a very small air gap between these two elements.

In these embodiments of the invention, it is necessary for the ratio of pulse energization or counter-energization to the constant energization to remain very constant because the complete compensation for the constant flux depends on this. Only with such compensation does the switch retaining portion of the non-energized switch moving electromagnet exert the required zero holding force on the switch blade, while its holding force is greater than zero :both in the event of over-compensation and in that of undercompensation for the constant flux. Particularly when the switch moving energy pulse has a steep edge can over-compensation of the magnetic flux lead to the switch blade not being withdrawn from the non-energized switch moving magnet because of its inertia. For these reasons, the invention proposes that the pulse energized windingsand hence also the seriesconnected counter-energized Windingsand the constantly energized windings should all be connected to the same voltage source, preferably to a stabilized mains connecting device. As a result, any voltage drop in the mains will have a uniform eflYect on all the energized windings so that the above-mentioned ratio remains constant. Such voltage drops may occur in particular if a number of such switch arrangements according to the invention are connected in series and if all the switch blades have to be switched over at the same time.

It can be seen that the switch blade of the present invention includes two relatively short steel plates which are connected to one another at their firont edge. The bearing for the switch blade is formed by a flat rectangular connecting member with little inherent rigidity, such as a tongue of Vulkollan, one end of which is fitted between the two steel plates in the vicinity of the front edge of the blade, and the other end of which is connected to a fixed guide web. In the interest of providing a short switching-over time, the switch blade is made very short and the two steel plates forming its side faces bear against appropriate edges of the guide web in the vicinity of their free ends and serve both to stabilize their mounting and as guide plates for guiding the documents.

As can be seen from FIGURE 6, the voltage from the AC mains is rectified and stepped down to usable levels in a rectifying and transforming means 20. Current from the latter is fed to both of the constantly energized windings. Current from means 20 is also fed to winding selector 22 which selects which electromagnet means 4 or 5 will have its pulse energized winding activated. This selection is made according to which trough 6 or 7 to which items are to be transported and a signal significant of this fact appears at control terminal A. From the selector 22 current passes to pulse former 24 where a pulse is formed and then to pulse polarity reverser 2-6. At this point the current pulse is passed through the appropriate pulse energized winding.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. In an electromagnetic switch arrangement for conveyors of flat articles, such as letters or documents, and including a switch blade of ferromagnetic materials at least at its leading edge, and electromagnet means arranged at both sides in the region of the leading edge of the switch blade, the improvement wherein each electromagnet means includes a constantly energized portion and at least one pulse energized winding, and means for compensating for the constant magnetic flux in the particular magnet against which the switch blade is bearing when the opposite electromagnet means has its appropriate winding pulse energized.

2. An electromagnetic switch device, comprising in combination:

(a) a switch blade made of ferromagnetic material at least at its leading edge; and

(b) two electromagnet means, one on each side of the switch blade in the vicinity of the leading edge thereof and each including a first constantly energized portion for providing a switch blade-retaining flux, and a second selectively activated pulse energized portion for providing a switch blade-moving flux, and including means for compensating for the constant blade-retaining flux of the particular electromagnet means by which the switch blade is being retained when the second portion of the other electromagnet means is energized.

3. A device as defined in claim 2 wherein said electromagnet means are arranged to form a closed magnetic circuit together with the switch blade.

4. A device as defined in claim 2 wherein said first portions are arranged to produce oppositely directed magnetic fluxes in the air gaps between the blade and the electromagnet means.

5. A device as defined in claim 2 wherein said first portions each include at least one winding, said windings being electrically connected to one another, and further comprising a voltage source to which said windings are constantly connected.

6. A device as defined in claim 2 wherein said compensating means includes at least one counter energized winding connected to be energized at the same time as the pulse energized portion of the opposite electromagnet means.

7. A device as defined in claim 6 wherein each counter energized winding is electrically connected to the pulse energized portion of the opposite electromagnet means.

8. A device as defined in claim 3 wherein said first portions are arranged to produce oppositely directed magnetic fluxes in the air gaps between the blade and the electromagnet means, and said compensating means including the reluctance of the switch blade being sufliciently high that the magnetic flux which passes through it from the pulse energized portion of one electromagnet means into the pulse energized portion of the other electromagnet means is great enough to compensate for the blade-retaining flux of this other electromagnet means.

9. A device as defined in claim 7 comprising a voltage source means connector, said constantly energized pottions and said pulse energized portions being connected to said connector so that the ratio of the energizing power for the first portions of the electromagnet means to the energizing power for the other portions of the electromagnet means remains constant regardless of vari m ations in load and voltage.

10. A device as defined in claim 2 comprising a fixed guide web, said switch blade including two steel plates connected to one another at their leading edge, and a flat rectangular connecting tongue having little inherent rigidity for mounting the switch blade and one end thereof being fitted between the two steel plates in the 5 web in the vicinity of their free ends.

12. A device as defined in claim 2 wherein said electromagnet means including E-shaped cores which face.

one another.

References Cited by the Examiner FOREIGN PATENTS 1,103,250 3/1961 Germany.

15 EVON c. BLUNK, Primary Examiner.

E. A. SROKA, Assistant Examiner. 

1. IN AN ELECTROMAGNETIC SWITCH ARRANGEMENT FOR CONVEYORS OF FLAT ARTICLES, SUCH AS LETTERS DOCUMENTS, AND INCLUDING A SWITCH BLADE OF FERROMAGNETIC MATERIALS AT LEAST AT ITS LEADING EDGE, AND ELECTRIMAGNET MEANS ARRANGED AT BOTH SIDES IN THE REGION OF THE LEADING EDGE OF SWITCH BLADE, THE IMPROVEMENT WHEREIN EACH ELECTROMAGNET MEANS INCLUDES A CONSTANTLY ENERGIZED PORTION AND AT LEAST ONE PULSE ENERGIZED WINDING, AND MEANS FOR COMPENSATING FOR THE CONSTANT MAGNETIC FLUX IN THE PARTICULAR MAGNET AGAINST WHICH THE SWITCH BLADE IS BEARING WHEN THE OPPOSITE ELECTROMAGNET MEANS HAS ITS APPROPRIATE WINDING PULSE ENERGIZED. 